This invention relates to a method of treating a part of the body of a patient with radioactive material, in which at least one hollow needle is introduced into the part of the body concerned, said needle being capable of subsequently receiving a tube containing selectively positioned radioactive material previously arranged therein, while using a cart comprising at least one tube containing selectively positioned radioactive material, an intermediate container for shielding the tubes and means for transporting the said tube with radioactive material into and out of the shielding means.